1. Field of the Invention
The invention relates to a device for the voltage supply in a motor vehicle and, more particularly, to a device for supplying voltage in a motor vehicle having two batteries.
2. Prior Art
Until now, the voltage supply in motor vehicles was typically done with the aid of a single battery charged by a generator. In modern motor vehicles with many electrical consumers, one battery is sometimes no longer sufficient for the voltage supply. To assure starting two separate batteries are used that are typically connected in parallel to one another. To assure that the two batteries are not cyclized at the same time and thus to prevent voltage drops that can occur during actuation of the starter at voltage-critical components, a charging/disconnection module is connected between the two batteries. This charging/disconnection device is provided in a device for voltage supply in a motor vehicle described in German Patent 41 38 943. During the starting process this module disconnects the battery associated with the starter from the rest of the on-board electrical system. Since the rated voltage of the battery assigned to the starter is somewhat lower than the rated voltage of the on-board electrical system battery, it is assured that the starter battery will be optimally charged at all times.